Help!
How would you solve 10 + 67 × 2?
I solved by putting a bracket between 10 and 67. Then multiplying by 2 Like this (10 + 67)2 = 154
However, others insist it's 144 and I'm wrong.
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3You multiply first, then add. This ambiguity is exactly why we use brackets. – Matthew Cassell Aug 16 '19 at 13:03
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1you do the multiplication first - so it's $67\times 5=335$, then $335+10=345$. – thesmallprint Aug 16 '19 at 13:04
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See this Wikipedia article – J. W. Tanner Aug 16 '19 at 13:05
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I think it's only natural one adds the bracket automatically considering the way the equation was written LRT – mamus eferha Aug 16 '19 at 13:07
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@mamuseferha you always follow order of operations. Even if it's written LTR with addition first, multiplication has higher precedence. – Andrew Li Aug 16 '19 at 13:08
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Okay @Andrew Li thank you – mamus eferha Aug 16 '19 at 13:10
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2Does $\ 10 + 67, x\ $ or other polynomials also "cause ruckus"? If not, why? – Bill Dubuque Aug 16 '19 at 13:20
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Before needing to ask another arithmetic question, as it relates to division and parentheses, I suggest also reading this question. – JMoravitz Aug 16 '19 at 13:20
3 Answers
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You can't write $(10+67)\cdot 2$ (because you add a $10$ that doesn't exist), but if you want to use brackets, you can say: $(67+10)\cdot 2-10=67+67+10+10-10=144$. Or $10=5\cdot 2$: $2\cdot (67+5)=144$.
Matteo
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If they meant $(10 + 67) \times 2$, they should have written that. Otherwise one should assume the standard order of operations is meant. Go to Wolfram Alpha and put in 10 + 67 * 2. It will answer 144 because there is nothing to indicate the addition should be done first.
Another possibility is that your friend is trying to create the next viral math formula. I suggest your friend should go back to the drawing board.
Robert Soupe
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